Chapter category: RNA
Aminoacyl-tRNA Synthetase Structure and Evolution
Translation Mechanisms
Edited by: Jacques Lapointe and Léa Brakier-GingrasISBN: 0-306-47839-0
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Chapter authors:
Dieter Söll and Michael Ibba
The pairing of codons in mRNA with tRNA anticodons determines the order of amino acids in a protein. It is therefore imperative for accurate translation that tRNAs are only coupled to amino acids corresponding to the RNA anticodon. This is mostly, but not exclusively, achieved by the direct attachment of the appropriate amino acid to the 3'-end of the corresponding tRNA by the aminoacyl-tRNA synthetases. To ensure the accurate translation of genetic information, the aminoacyl-tRNA synthetases must display an extremely high level of substrate specificity. Despite this highly conserved function, recent studies arising from the analysis of whole genomes have shown a significant degree of evolutionary diversity in aminoacyl-tRNA synthesis. For example, non-canonical routes have been identified for the synthesis of Asn-tRNA, Cys-tRNA, Gln-tRNA and Lys-tRNA. Characterization of noncanonical aminoacyl-tRNA synthesis has revealed an unexpected level of evolutionary divergence and has also provided new insights into the possible precursors of contemporary aminoacyl-tRNA synthetases.
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